Purpose: As it had never been done before, the purpose of this investigation was to correlate the mandibular growth-spurt in individuals with the sequential stage of calcification of the mandibular second and third molars, two years before and after the spurt peak. The sample consisted of 40 healthy Caucasians, equally divided as to sex, and all a part of a group participating in a longitudinal growth study at The Child Research Council, Denver, Colorado. Annual lateral and anteroposteriorly- oriented standardized roentgenograms were available on these subjects, who ranged from ages 3-18. Method: The lateral cephs were traced on acetate paper; midlines of the structures which were not coinciding, were traced. Three representative mandibular measurements were chosen: Overall mandibular length (Ar-Pog), ramus length (Ar-Go), and corpus length (Go-Pog), then measured in millimeters with a Boley gauge (pointed tips). Based on Nolla's ten calcification stages, sequential calcification stages of the mandibular second and third molars on each series were rated by graphical and statistical analyses. Incremental growth curves were plotted for each mandibular dimension measured to determine the timing of peak-of-spurt relative to chronological age. Stages of molar calcification were plotted on each incremental curve. An average of the timing of three dimensions was made of each subject and recorded on a frequency chart, plotting calcification stages with puberty. Statistical analysis was done for the reliability of the measurements and ratings of calcification. A Chi-square and contingency coefficient would establish the degree of relationship of pubertal growth spurt and stages of calcification. Findings: A study of this nature would (1) Enable the prediction of timing of pubertal growth spurt, utilizing sequential stages of tooth calcification; (2) Give information about the amount of remaining growth in individuals; (3) Ensure proper timing of orthodontic treatment and anticipation of results from final information derived from the study.